U.S. Pat. No. 3,402,684 is directed to a process to provide bark from an atmospheric pressure portion to a subatmospheric pressure portion.
WO-A-99/66008 describes a fixed bed gasification reactor for municipal waste.
In a coal gasification process pulverised coal is fed to a pressurised gasification reactor either as a dry solid or as a slurry. A commercial process to pressurize dry pulverised coal comprises the use of a lock hopper as described in Chapter 6.2 in Gasification, by Christopher Higman and Maarten van der Burgt, 2003, Elsevier Science, Burlington Mass., Pages 173-177. A disadvantage of using such a lock hopper design is the cycling of multiple batch tanks, the disruptions that occur when one such tank is taken off line and another is started and the venting of significant quantities of pressurising gas. The same textbook mentions on pages 182-183 solids pumping as an alternative. It is described that many types of equipment have been developed but thus far none have been very successful because they are vulnerable for erosion and fouling. Examples of solid pump systems in which Maarten van der Burgt, one of the authors of this reference book, was named as inventor are EP-A-038597 and EP-A-029262.
The solids pump as described in U.S. Pat. No. 5,657,704 seems to have more potential for actual commercial application, because the design of this solids pump seems less vulnerable for fouling and erosion than the earlier and above referred to designs. This publication describes a method for continuously supplying solids from a lower pressure storage reservoir to a high-pressure feeder tank using a solids pump. From the feeder tank the solids are transported to a high-pressure blast furnace. The solids pump according to this publication is preferably a high pressure solids pump available from STAMET Incorporated. Publications describing such a pump are U.S. Pat. No. 4,516,674, U.S. Pat. No. 4,988,239 and U.S. Pat. No. 5,051,041.
A disadvantage of the process of U.S. Pat. No. 5,657,704 is the presence of a high-pressure feeder tank between the solids pump and the pressurised reactor. Because of this intermediate feeder tank it is not possible to directly control the flow of solids to the pressurised reactor by controlling the rotational speed of the solids pump itself. The control of solids is especially critical when the pressurised reactor is a gasification reactor. In such a process the ratio of oxygen to carbon has to be kept within certain ranges in order to maximise the production of carbon monoxide and hydrogen.
It would be an advancement in the art to provide a process to provide a particulate solid carbonaceous material to a pressurised gasification reactor, which does not have the above-mentioned problem.